(1) Field
The disclosed methods and systems relate generally to routing schemes, and more particularly to routing techniques that improve network lifetime and latency.
(2) Description of Relevant Art
Ad-hoc networks generally can be understood to be a collection of wireless hosts forming a temporary network without the support of centralized administration and/or support services typically associated with infrastructure-based networks such as wide area networks. Mobile ad hoc networks extend the notion of ad hoc networks to include cases where nodes are allowed to move relative to each other such that the routing topology itself is dynamic. As provided herein, ad hoc networks and mobile ad hoc networks will be referred to collectively as ad hoc networks.
Ad hoc networks can be used, for example, in an emergency situation where emergency personnel may need unencumbered access to situational awareness information and/or to share information with others. Given the likely disruption of public communications infrastructure due to, for example, subscriber overload during crisis situations, the use of wireless communication devices is essential to emergency personnel. Ideally, these wireless devices should be portable, lightweight, and have long battery life. As a result, these devices have limited range. The aforementioned ad-hoc networks allow for multi-hop configurations so that users who are otherwise out of range of each other can still communicate.
The lifetime of an ad hoc network as a whole is clearly subject to the battery capacity of constituent node devices. Moreover, not only are the bandwidths of these wireless devices necessarily limited, but the capacity of any given wireless link is in general varies as a function of the signal-to-noise ratios observed between the end nodes. Routing algorithms should therefore consider link capacity, available node energy, and traffic load in optimizing the performance of ad hoc networks.
Traditional “shortest path” schemes that are employed in ad-hoc network routing typically yield routing topologies where small numbers of network paths are heavily used. Such schemes can cause path contention, which increases latency through queueing delay, reduces throughput, and induces disproportionately heavy leads on a few network nodes (e.g., devices). Uneven loading can cause premature network failure due to accelerated draining of node device batteries at one or more critical nodes.
Some research regarding ad-hoc network routing includes energy conservation routing techniques to ameliorate the aforementioned battery problem; however, such energy routing techniques if used by themselves as standalone algorithms can more than triple latency, create energy-wasting routing loops, and are sensitive to traffic load assumptions.